Confocal imaging using astigmatism

ABSTRACT

The present disclosure provides computing device implemented methods, apparatuses, and computing device readable media for confocal imaging using astigmatism. Confocal imaging can include receiving an image of a portion of an object captured by a confocal imaging device having a particular astigmatic character, determining an image pattern associated with the image, and determining a distance between a focus plane of the confocal imaging device and the portion of the object based, at least in part, on information regarding the image pattern. Confocal imaging can also include receiving data representing an image pattern associated with an image of an object captured by a confocal imaging device having a particular astigmatic character and having an image sensor with a plurality of pixels, and determining a positional relationship between the object and a focus plane of the confocal imaging device based on a distribution of the diffraction pattern over a portion of the plurality of pixels.

BACKGROUND

The present disclosure is related generally to the field of 3D imagingand particularly 3D imaging useful in fields such as dentistry. Moreparticularly, the present disclosure is related to methods, apparatuses,and devices for confocal imaging using astigmatism.

It may be valuable to perform 3D scans of objects for many purposes,such as record keeping, making duplicates, and/or modifying theresultant digital images for various purposes, such as improving adesign of the object or for treatment purposes, for example, if theobject is part of a human body. One example related to the field ofdentistry is to use such a scanned digital image for either recordkeeping or for treatment purposes. Dental treatments may involve, forinstance, restorative (e.g., prosthodontic) and/or orthodonticprocedures.

Restorative and/or prosthodontic procedures may be designed to implant adental prosthesis (e.g., a crown or bridge) in the intraoral cavity of apatient or to plan for veneers for a patient's teeth, for instance.Orthodontic procedures may include repositioning misaligned teeth andchanging bite configurations for improved cosmetic appearance and/ordental function. Orthodontic repositioning can be accomplished, forexample, by applying controlled forces to one or more teeth over aperiod of time.

With computing device-aided teeth treatment systems, an initial digitaldata set (IDDS) representing an initial tooth arrangement may beobtained. The IDDS may be obtained in a variety of ways.

For example, the patient's teeth may be imaged to obtain digital datausing direct and/or indirect structured light, X-rays, three-dimensionalX-rays, lasers, destructive scanning, computing device-aided tomographicimages or data sets, magnetic resonance images, intra-oral scanningtechnology, photographic reconstruction, and/or other imagingtechniques. The IDDS can include an entire mouth tooth arrangement,some, but not all teeth in the mouth, and/or it can include a singletooth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an apparatus including a confocal imaging deviceaccording to a number of embodiments of the present disclosure.

FIGS. 2A-2B illustrate a horizontal image pattern and a vertical imagepattern, respectively, on a portion of an image sensor according to anumber of embodiments of the present disclosure.

FIG. 3 is a flow chart illustrating a method for confocal imaging usingastigmatism according to a number of embodiments of the presentdisclosure.

FIG. 4 illustrates a system for confocal imaging using astigmatismaccording to a number of embodiments of the present disclosure.

DETAILED DESCRIPTION

A number of objects (e.g., 3 dimensional objects) may be scanned, forexample, using a parallel confocal imager (e.g., scanner). With such animager, multiple frames can be captured, each frame creating a depthsection of the measured space, for instance. Multiple depth sections canallow for renderings of 3D reconstructions of the object(s). 3Dreconstructions can be used for various purposes, such as, for example,the creation of physical models of the scanned object. 3Dreconstructions can be stored in memory and/or converted to various dataformats. In various embodiments, a scanning system may be used to obtaindigital data representing a patient's teeth in their then currentposition (i.e., at the time of the scan) which can be considered, asused herein, an initial digital data set (IDDS) representing an initialtooth arrangement. An IDDS can be used for dental records and/ortreatment purposes, for instance.

Embodiments of the present disclosure can determine (e.g., measureand/or render) surface topology of various objects. Although variousembodiments are described herein with respect to the context of dentalimaging and/or treatment, embodiments of the present disclosure are notso limited and can be used in various contexts.

Various embodiments can determine a location of a particular portion(e.g., a point location of a surface) of an object over a range ofdistances between the portion and a focus plane of a confocal imagingdevice. Accordingly, embodiments of the present disclosure can reduce anumber of positions at which the focus plane is placed with respect tothe object during frame capture. It may be desirable to reduce a numberof frames captured to obtain a particular level of scan precision,quality and/or performance. For example, in the practice of intra-oralscanning, reducing scan duration can increase patient comfort and/orsatisfaction. Further, reducing scan duration can provide directbenefits to a treating professional by permitting a scan to be simplerand/or faster. While such a reduction can lessen time spent actuallyacquiring frames, it can additionally reduce computational and/orcommunication loads associated with scanning. A reduction in framecaptures can quicken computation and/or simplify scanning processes.Such a reduction can improve methods of scanning while the scanner ismoving with respect to the teeth, for instance.

Point image pattern (e.g., point spread function (PSF), referred togenerally herein as “image pattern,” can be a smallest pattern to whichan optical system at a particular configuration focuses a beam of light(e.g., light originating from a point object) upon a two-dimensionalsurface perpendicular to a path of the light. In non-astigmatic systems,an image pattern (e.g., a well-focused image pattern) can be referred toas an Airy pattern. An Airy pattern can be considered to be the bestfocused spot of light that a perfect lens with a circular aperture canmake, limited only by the diffraction of light, for instance.

Astigmatism, as used herein, refers to an instance in various opticalsystems where light rays propagating in two perpendicular planes (e.g.,a tangential plane and a sagittal plane) exhibit different foci (focalplanes). As a result, an image of a point object that is out-of-focus inan astigmatic system may have a noncircular and/or circularly asymmetricimage pattern (e.g., an image pattern that is substantially oblong,elliptical, and/or oval-shaped). That is, an out-of-focus astigmaticimage pattern has perpendicular (e.g., substantially perpendicular) axesof differing lengths.

For example, in a focused astigmatic system, as the system goesout-of-focus in a first direction (e.g., the object moves closer to theoptical system) the image pattern may become elliptic with its majoraxis in a first orientation (e.g., horizontal). As the system goesout-of-focus in a second direction (e.g., the object moves away from theoptical system), the image pattern may become elliptic with its majoraxis in a second orientation (e.g., vertical), perpendicular to thefirst orientation.

For an astigmatic image pattern, a ratio between the length of its majoraxis and the length of its perpendicular axis may relate to a value ofthe focus error (e.g., a distance from focus). The orientation of themajor axis may relate to the direction of the focus error (e.g., whetherthe object is too far or too near).

Embodiments of the present disclosure may include a particular and/orpredetermined astigmatic character. A particular astigmatic charactercan include an astigmatic character that causes light to form an imagepattern in a particular and/or predetermined manner. A particularastigmatic character can be created by an astigmatic aberration in alight path of the optical system. Astigmatic aberrations include, forexample, weak cylindrical lenses, toroidal optical surfaces (e.g.,barrel and/or doughnut shaped surfaces), and/or the inclusion of a flatwindow having a surface oblique (e.g., not perpendicular) to an axis ofthe optical system, among others. Astigmatic aberrations, as referred togenerally herein, can include devices causing an optical system to havean astigmatic character.

The present disclosure provides computing device implemented methods,apparatuses, and computing device readable media for confocal imagingusing astigmatism. Such confocal imaging using astigmatism can includereceiving an image of a portion of an object captured by a confocalimaging device having a particular astigmatic character, determining animage pattern associated with the image, and determining a distancebetween a focus plane of the confocal imaging device and the portion ofthe object based, at least in part, on information regarding the imagepattern.

Confocal imaging using astigmatism can include scanning a surface of athree-dimensional object at a first scan setting with a scanner having aparticular astigmatic character to obtain a first plurality of imagepatterns, wherein each image pattern of the first plurality correspondsto a respective portion of the surface, determining a first positionalrelationship between each respective portion and the scanner based onthe first plurality of image patterns, scanning the surface of thethree-dimensional object with the scanner at a second scan setting toobtain a second plurality of image patterns, determining a secondpositional relationship between each respective portion and the scannerbased on the second plurality of image patterns, and generating datarepresentative of a topology of the surface of the three-dimensionalobject based on the first positional relationships and the secondpositional relationships.

In some or all embodiments, an apparatus for confocal imaging usingastigmatism can include a confocal imaging device having a predeterminedastigmatic aberration disposed in a light path thereof to asymmetricallyfocus light in a predetermined manner, wherein the light is associatedwith an image of a portion of an object captured by the confocal imagingdevice.

Confocal imaging using astigmatism can also include receiving datarepresenting an image pattern associated with an image of an objectcaptured by a confocal imaging device having a particular astigmaticcharacter and having an image sensor with a plurality of pixels, anddetermining a positional relationship between the object and a focusplane of the confocal imaging device based on a distribution of thediffraction pattern over a portion of the plurality of pixels.

In the detailed description of the present disclosure, reference is madeto the accompanying drawings that form a part hereof, and in which isshown by way of illustration how one or more embodiments of thedisclosure may be practiced. These embodiments are described insufficient detail to enable those of ordinary skill in the art topractice the embodiments of this disclosure, and it is to be understoodthat other embodiments may be utilized and that process, electrical,and/or structural changes may be made without departing from the scopeof the present disclosure. As used herein, “a number of” a particularthing can refer to one or more of such things (e.g., a number of pixelscan refer to one or more pixels).

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 100 may referenceelement “00” in FIG. 1, and a similar element may be referenced as 400in FIG. 4. As will be appreciated, elements shown in the variousembodiments herein can be added, exchanged, and/or eliminated so as toprovide a number of additional embodiments of the present disclosure. Inaddition, as will be appreciated, the proportion and the relative scaleof the elements provided in the figures are intended to illustratecertain embodiments of the present invention, and should not be taken ina limiting sense.

FIG. 1 illustrates an apparatus including a confocal imaging device 100according to a number of embodiments of the present disclosure. Confocalimaging device 100 can be a hand-held intraoral scanner, for instance;though, as previously discussed, the present disclosure is not limitedto dental applications and/or embodiments. As shown in FIG. 1, confocalimaging device 100 can include a light source array 102, a sourcelenslet array 104, a beam splitter 114, an object lenslet array 110, animage lenslet array 118, and an image sensor 122.

Confocal imaging devices in accordance with the present disclosure arenot limited to the components illustrated in FIG. 1. Variousarrangements calculated to achieve the same techniques can besubstituted for the embodiment illustrated in FIG. 1. For example,embodiments of the present disclosure can include components notillustrated in FIG. 1 (e.g., a housing, etc.). Further, the number(s) ofthe various components illustrated in FIG. 1 are not to be taken in alimiting sense. For example, though light source array 102 is shown asincluding a particular number of light sources (e.g., ten), embodimentsof the present disclosure are not limited to a particular number oflight sources and/or light source arrays. A path traveled by light 108through confocal imaging device 100, as illustrated in FIG. 1, may beherein referred to as a “light path.”

An astigmatic aberration can be associated with (e.g., positioned atand/or within) various locations within the light path illustrated inFIG. 1 to create a particular astigmatic character in confocal imagingdevice 100. In various embodiments, an aberration can be adjacent tolight source array 102 and/or associated with source lenslet array 104(e.g., one or more lenslets in the light path between light source array102 and beam splitter 114). In some or all embodiments, an aberrationcan be adjacent to image sensor 122 and/or associated with image lensletarray 118 (e.g., one or more lenslets in the light path between beamsplitter 114 and image sensor 122). As discussed herein, an astigmaticaberration can asymmetrically focus light 108 such that a particularasymmetric image pattern can be shone upon, and received by, imagesensor 122. For purposes of illustration, the discussion herein ofconfocal imaging device 100 includes an astigmatic aberration associatedwith image lenslet array 118; though, as previously discussed,embodiments of the present disclosure are not so limited.

Light source array 102 in some or all embodiments can be and/or includevarious light sources, including, for example, continuous wave lasers,air ion lasers, semiconductor lasers, etc. Light source array 102 caninclude a number of individual light sources and/or a number ofcomponents configured to produce a number of light beams (e.g., 100,000light beams). For example, a plurality of incident light beams can beproduced at light source array 102 by splitting a parent beam. Lightsource array 102 can include a plurality of light emitters, eachconfigured to emit a single light beam, for instance. Light source array102 can include various refraction and/or diffraction componentsconfigured to produce a plurality of light beams. For purposes ofillustration, a single light beam, light 108 (e.g., a portion of lightemitted by light source array 102), is shown in FIG. 1, and its paththrough confocal imaging device 100 is discussed herein.

Source lenslet array 104 in some or all embodiments can collimate and/orfocus light 108 via a number of lenslets (e.g., microlenses). Beamsplitter 114 can selectively separate light 108. For example, dependingon various properties of beam splitter 114, light 108 (e.g., all or partof light 108) can pass through beam splitter 114 unreflected, asdiscussed below, for instance.

Light 108 can be emitted from light source array 102 and be focusedand/or collimated by source lenslet array 104. Thereafter, it can bereflected by (e.g., partially reflected by) beam splitter 114, focusedby a respective lenslet in object lenslet array 110 to a point (e.g.,near point) at focus plane 116. As illustrated in FIG. 1, focus plane116 can be located at various positions with respect to portions of anobject 112. Object 112 can be and/or include various objects, such as,for example, a tooth. Portions of object 112 can be nearer to, fartherfrom, and/or equidistant from object lenslet array 110 than focus plane116. Where a particular portion of object 112 illuminated by light 108is equidistant from object lenslet array 110, it can be considered to be“on” focus plane 116. Light 108 reflecting from a portion of object 112that is on focus plane 116 can be re-collimated (e.g., refocused) byobject lenslet array 110. Light 108 reflecting from portions of object112 that are not on focus plane 116 can diverge and/or convergedepending on whether such portions are nearer to, and/or farther from,object lenslet array 110 than focus plane 116 for instance, in additionto various configurable settings of confocal imaging device 100.

Light 108 can reflect off of object 112, be re-collimated by objectlenslet array 110, and can pass through (e.g., pass through unreflected)beam splitter 114 towards a respective lenslet of image lenslet array118, where it can be collimated and/or focused onto (e.g., received by)a number of pixels of image sensor 122. Image sensor 122 can be a device(e.g., Charge Coupled Device (CCD), Complimentary Metal OxideSemiconductor (CMOS), etc.) configured to convert an optical image(e.g., an image pattern associated with light 108) to an electronicsignal via, for example, a number of pixels discussed further below inconnection with FIGS. 2A and/or 2B. Once received by image sensor 122,light 108 (e.g., the image pattern associated with light 108) can, forexample, be used for various determinations such as those discussedfurther below.

As previously discussed, various lenslets of image lenslet 118 can havea particular astigmatic character (e.g., aberration). Accordingly,converging and/or diverging incoming rays of light 108 reflected fromobject 112 can produce oblong and/or ellipse-like image patterns on anumber of pixels of image sensor 122 (discussed further below inconnection with FIGS. 2A and/or 2B). An orientation (e.g., direction) ofa major axis of such ellipse-like image patterns may depend on whetherlight 108 is diverging or converging as it is received by image sensor122. Accordingly, the orientation of the major axis, in variousembodiments, can indicate a position, with respect to focus plane 116,of the particular portion of object 112 illuminated by light 108. Forexample, embodiments of the present disclosure can determine whether theilluminated portion of object 112 was closer to, or further from, objectlenslet array 110 than focus plane 116.

Additionally, embodiments of the present disclosure can determinevarious intensities of light 108 received at each of a number of pixelsof image sensor 122. Accordingly, embodiments of the present disclosurecan determine a magnitude of a distance between a particular portion ofobject 112 and focus plane 116. A “positional relationship,” as usedherein, can refer to a distance between a particular portion of object112 and focus plane 116 (or confocal imaging device 100), and/or whetherthe particular portion of object 112 is nearer to, farther from, and/orequidistant from object lenslet array 110 (or confocal imaging device100) than focus plane 116.

A single beam of light (light 108) is illustrated in FIG. 1 as beingemitted by light source array 102. In various embodiments, additionallight beams can be emitted from light source array 102 and can bereflected at various locations along beam splitter 114 towardsrespective lenslets of object lenslet array 110. Thus, a number ofportions of object 112 can be illuminated simultaneously, for instance,and a number of positional relationships can be determined along asurface of object 112. Such relationships can be used to generate datarepresentative of a topology of the surface of object 112, for instance.

Focus plane 116 (sometimes generally referred to herein as “scansetting”) can be adjusted during a scan using confocal imaging device100. Such adjustment can be carried out in various manners. For example,a number of servo motors can be used to manipulate a number of theoptical components of confocal imaging device 100 (e.g., object lensletarray 110). Adjusting can include moving confocal imaging device 100towards and/or away from object 112. Adjusting can be programmed and/orperformed in accordance with computer-executable instructions (discussedbelow) such that a plurality of scan settings are equally spaced and/orsequential, for instance. Further, embodiments of the present disclosurecan include a plurality of focus planes (e.g., each associated with arespective light path); such focus planes can be adjusted simultaneously(e.g., by moving confocal imaging device 100) and/or individually, forinstance.

FIGS. 2A-2B illustrate a horizontal image pattern (e.g., distribution oflight in an image of a point object) 250-A and a vertical image pattern250-B, respectively, on a portion of an image sensor (portion 222-A andportion 222-B, respectively). Horizontal image pattern 250-A andvertical image pattern 250-B can represent situations in which an imageis defocused (e.g., out-of-focus) in an astigmatic system (e.g., system100 previously discussed in connection with FIG. 1). It is noted thatFIG. 2A and FIG. 2B each illustrate single image patterns (e.g.,associated with light 108) on a portion of an image sensor, thoughembodiments are not so limited. For example, multiple image patterns maybe formed simultaneously on image sensors in accordance with the presentdisclosure.

As shown, horizontal image pattern 250-A and vertical image pattern250-B are substantially oblong and/or ellipse-like, having perpendicularaxes of differing lengths. Such shapes may be contrasted, for instance,with substantially circular defocused image patterns created bynon-astigmatic systems.

FIG. 2A illustrates a portion 222-A of the image sensor (e.g., imagesensor 122 previously discussed in connection with FIG. 1) receiving ahorizontal image pattern 250-A. As shown in FIG. 2A, portion 222-Aincludes a number of pixels 232, 234, 236, 238, 240, 242, 244, 246, and248, sometimes generally herein referred to as pixels 232-248. As shownin FIG. 2A, horizontal image pattern 250-A has a major axis orientedhorizontally. Horizontal, as used herein, refers to a particularorientation and is used for illustrative purposes to indicate anorientation of a major axis of an image pattern with respect to a numberof pixels of an image sensor.

It is noted that FIGS. 2A and 2B illustrate a particular number ofpixels (e.g., nine pixels arranged in a 3×3 grid). However, embodimentsof the present disclosure are not limited to a particular number ofpixels. Similarly, embodiments of the present disclosure are not limitedwith respect to a number of pixels configured to receive an imagepattern; rather, various numbers of pixels can be selected and/orarranged to receive image patterns.

FIG. 2B illustrates a portion 222-B of the image sensor illustrated inFIG. 2A receiving a vertical image pattern 250-B. As shown in FIG. 2B,portion 222-B includes the number of pixels 232-248. As shown in FIG.2B, vertical image pattern 250-B has a major axis oriented vertically.Vertical, as used herein, refers to a particular orientation and is usedfor illustrative purposes to indicate an orientation of a major axis ofan image pattern with respect to a number of pixels of an image sensor.

As shown in FIG. 2A, horizontal image pattern 250-A covers (e.g., lightof image pattern 250-A strikes) pixel 240, and horizontal image pattern250-A covers a portion of pixel 238 and a portion of pixel 242. As shownin FIG. 2B, vertical image pattern 250-B covers pixel 240 and a portionof pixel 234 and a portion of pixel 246. Pixels 232-248 can each containa photo-detector and/or an active amplifier, among other circuitry, andcan convert light energy (e.g., from image pattern 250-A and/or 250-Binto an electric signal. Data from the electric signal can be saved inmemory and/or processed by a computing device in a manner analogous tothat discussed below, for instance.

Embodiments of the present disclosure can determine contextualinformation associated with defocused images based on orientations ofimage patterns. For example, horizontal image pattern 250-A may bereceived in a situation where an object (e.g., a portion of an objectilluminated by a particular light beam) is proximal to a focal plane ofa confocal imaging device (e.g., defocused in a first direction). Forexample, and with reference to FIG. 1, horizontal image pattern 250-Acan indicate that an illuminated portion of object 112 is nearer toobject lenslet array 110 than is focus plane 116.

Accordingly, vertical image pattern 250-B may be received in a situationwhere the object is beyond the focal plane of the confocal imagingdevice (e.g., defocused in a second direction). For example, and withreference to FIG. 1, vertical image pattern 250-B can indicate thatobject 112 is farther from object lenslet array 110 than is focus plane116.

Confocal imaging devices according to the present disclosure in some orall embodiments are not limited to a particular configuration.Accordingly, image patterns are not limited to a particular orientation(e.g., horizontal and/or vertical). Further, relationships betweenorientations of image patterns and focal planes are not limited to theexamples presented herein (e.g., horizontal image pattern 250-A can beassociated with an object beyond the focus plane and vertical imagepattern 250-B can be associated with an object proximal to the focusplane).

Embodiments of the present disclosure can differentiate betweendirections of defocus. As previously discussed, light rays in anastigmatic system propagate in two perpendicular planes having differentfocal lengths. The two focal lengths, f_(x) and f_(y), respectively, canrefer to focal lengths of the vertical and horizontal image planes,though it is again noted that the illustrative use of “vertical” and“horizontal” herein merely indicates that the planes are perpendicular.

A distance S, can be defined as a distance between an object point and afront principle plane of an astigmatic lens. Another distance, S′_(x),can be defined as a distance between a rear principle plane of the lensand the horizontal image plane (e.g., where the image pattern becomesnearly a vertical line). Another distance, S′_(y), can be defined as adistance between the rear principle plane of the lens and the verticalimage plane (e.g., where the image pattern becomes nearly a horizontalline). Accordingly:

$\quad\{ \begin{matrix}{\frac{1}{f_{x}} = {\frac{1}{S} + \frac{1}{S_{x}^{\prime}}}} \\{\frac{1}{f_{y}} = {\frac{1}{S} + \frac{1}{S_{y}^{\prime}}}}\end{matrix} $It is noted that if the lens discussed above is a substantially thinlens, both principle planes can merge into the plane of the lens itself.

If an image sensor is positioned at a distance {tilde over (S)} from therear principle plane, the size of the two axes of the resultingelliptical image pattern (e.g., of a point object) can be d_(x) andd_(y), given by:

$\quad\{ \begin{matrix}{d_{x} \cong {{\frac{\overset{\sim}{S} - S_{x}^{\prime}}{S_{x}^{\prime}}}D}} \\{d_{y} \cong {{\frac{\overset{\sim}{S} - S_{y}^{\prime}}{S_{y}^{\prime}}}D}}\end{matrix} $where D is a diameter of the lens. Values generated for d_(x) and d_(y)can be considered substantially accurate provided that |{tilde over(S)}−S′_(x)| and |{tilde over (S)}−S′_(y)| are substantially largerelative to a light wavelength λ (e.g., a wavelength of light 108).

Based on the non-astigmatic lens and image sensor relationships,astigmatic confocal depth (e.g., distance between the confocal imagingdevice and the object) can be determined. For example, a particularlenslet can be associated with a number of pixels of an image sensor(e.g., 3×3 pixels), numbered as:

-   -   g_(m−1,n−1) g_(m−1,n) g_(m−1,n+1)    -   g_(m,n−1) g_(m,n) g_(m,n+1)    -   g_(m+1,n−1) g_(m+1,n) g_(m+1,n+1)        where g_(m,n)-th pixel is centered on the axis of the lenslet.        The above matrix can be analogous to the arrangement of pixels        232-248 illustrated in FIGS. 2A and/or 2B, wherein, as shown,        pixel 240 is centered in the axis of the lenslet. An intensity        (e.g., a relative intensity) of the light received at the above        pixels can correlate to a focus shift (e.g., a distance of the        object from the focus plane). The intensity can be measured by        an electric charge produced in the pixels, for instance. The        electric charge, e_(m,n), can be determined by:

$e_{m,n} = \frac{( {g_{{m - 1},n} + g_{{m + 1},n}} ) - ( {g_{m,{n - 1}} + g_{m,{n + 1}}} )}{\sum\limits_{m^{\prime} = {m - 1}}^{m + 1}\;{\sum\limits_{n^{\prime} = {n - 1}}^{n + 1}\; g_{m^{\prime},n^{\prime}}}}$The actual shift in the distance of the object, ΔS, can be determinedfrom the electric charge e_(m,n) by theoretical calculation and/or byusing a previously calculated look-up-table and/or interpolationfunction.

As the focus shift ΔS increases, the resulting image pattern mayincrease in size. In various embodiments, a particular increase in sizemay be avoided. For example, portions of the image pattern may cover(e.g., partially cover) adjacent pixels beyond the selected 3×3 pixels.Further, as the focus shift ΔS increases, an amount of light reachingeach pixel may not exceed a particular threshold (e.g., may beinsufficient for proper pixel reception). An image pattern can belimited in size through the conditions:

$\quad\{ \begin{matrix}{\mu_{m,n} > \mu_{\min}} \\{\sigma_{m,n}^{2} > \sigma_{\min}^{2}}\end{matrix} $where

$\sigma_{m,n}^{2} = {\frac{1}{9}{\sum\limits_{m^{\prime} = {m - 1}}^{m + 1}\;{\sum\limits_{n^{\prime} = {n - 1}}^{n + 1}\;( {g_{m^{\prime},n^{\prime}} - \mu_{m,n}} )^{2}}}}$$\mu_{m,n} = {\frac{1}{9}{\sum\limits_{m^{\prime} = {m - 1}}^{m + 1}\;{\sum\limits_{n^{\prime} = {n - 1}}^{n + 1}\; g_{m^{\prime},n^{\prime}}}}}$

and where σ_(min) ² and μ_(min) can be pre-set threshold values, forinstance.

FIG. 3 is a flow chart illustrating a method 360 for confocal imagingusing astigmatism according to a number of embodiments of the presentdisclosure. Method 360 can be performed by computing device 474,discussed below in connection with FIG. 4, for instance.

At block 362, a portion of an object (e.g., a surface of athree-dimensional object) can be illuminated using a non-astigmaticconverging beam of light by a confocal imaging device (e.g., scanner) ata first scan setting. Such illumination can occur, for instance, aspreviously discussed in connection with FIG. 1 (e.g., illuminating aportion of object 112 with light 108). In various embodiments, and aspreviously discussed, multiple beams of light can be used to illuminateportions of the object. Accordingly, a surface of the three-dimensionalobject can be scanned with a scanner having a particular astigmaticcharacter to obtain a first plurality of images at a first scan setting,wherein each image of the first plurality corresponds to a respectiveportion of the surface.

At block 364, an image pattern of the illuminated portion can be formedon an image sensor including a number of pixels using an astigmaticaberration. Such formation can be analogous to that previouslydiscussed, for instance. In various embodiments, a first set of imagepatterns can be determined from a first plurality of images.

At block 366, a determination can be made regarding whether an intensityof the image pattern (e.g., an intensity of the light forming the imagepattern) exceeds a particular threshold. A threshold can be associatedwith a particular electric charge produced by a number of pixels. Such athreshold can be user-determined, for instance, and/or based on variousproperties of the pixel(s) and/or associated circuitry. An intensity notexceeding the threshold may be insufficient for proper pixel reception,for instance, and may indicate that the portion of the object exceeds aparticular distance from focus (e.g., too far from focus for an imagepattern to be properly received).

At block 368, if a determination is made that the intensity did notexceed the threshold, the confocal imaging device can be adjusted to anext (e.g., second) scan setting (e.g., as discussed above) whereuponthe object can be illuminated using the non-astigmatic converging beamof light at the second scan setting. Various embodiments using multiplelight beams can include scanning a surface of a three-dimensional objectat a first scan setting with a scanner having a particular astigmaticcharacter to obtain a first plurality of image patterns, wherein eachimage pattern of the first plurality corresponds to a respective portionof the surface. Embodiments herein are not limited to a particularnumber of images and/or scan settings, nor are embodiments limited to aparticular number of images captured per scan setting.

If, at block 366, the intensity of the image pattern was determined tohave exceeded the threshold, an intensity of the image pattern (e.g., alevel of electric charge of a pixel nearest to a center of the imagepattern) can be determined from a number of pixels of the image sensor(e.g., as discussed above in connection with FIGS. 2A and/or 2B) atblock 370. Various embodiments of the present disclosure includedetermining a second set of image patterns from the second plurality ofimages. Intensities of image patterns can be determined from (e.g.,based on) various images at various scan settings.

Accordingly, at block 372, a distance between the portion of the objectand a focus plane of the confocal imaging device (e.g., a positionalrelationship) can be determined based on information regarding the imagepattern (e.g., the intensity of the image pattern). Such a determinationcan be made in a manner analogous to that previously discussed, forinstance. Determining distances (e.g., a plurality of distances over asurface of the object) can include determining a first positionalrelationship between each respective portion and the scanner based on afirst plurality of image patterns (e.g., received at the first scansetting).

Further, the scanner can be adjusted to a second scan setting and usedto scan the surface of the three-dimensional object with at the secondscan setting to obtain a second plurality of image patterns. A secondpositional relationship between each respective portion and the scannercan be determined based on the second plurality of image patterns. Datarepresentative of a topology of the surface of the three-dimensionalobject can be generated based on the first positional relationships andthe second positional relationships, for instance, though embodiments ofthe present disclosure are not limited to a particular number of scansettings, image patterns, and/or positional relationships used togenerate such data.

FIG. 4 illustrates a system for confocal imaging using astigmatismaccording to a number of embodiments of the present disclosure. Thesystem illustrated in FIG. 4 can include a computing device 474 having anumber of components coupled thereto. The computing device 474 caninclude a processor 476 and memory 478. The memory 478 can includevarious types of information including data 480 and executableinstructions 482 as discussed herein.

The memory 478 and/or the processor 476 may be located on the computingdevice 474 or off the device in some embodiments. As such, asillustrated in the embodiment of FIG. 4, a system can include a networkinterface 484. Such an interface can allow for processing on anothernetworked computing device or such devices can be used to obtaininformation about the patient or executable instructions for use withvarious embodiments provided herein.

As illustrated in the embodiment of FIG. 4, a system can include one ormore input and/or output interfaces 486. Such interfaces can be used toconnect the computing device 474 with one or more input or outputdevices.

For example, in the embodiment illustrated in FIG. 4, the systemincludes connectivity to a scanner 400 (e.g., a confocal imaging deviceas described herein), an input device 488 (e.g., a keyboard, mouse,etc.), a display device 490 (e.g., a monitor), and a printer 492. Theinput/output interface 486 can receive data 480, storable in the datastorage device (e.g., memory 478), representing data corresponding to anumber of images (e.g., of patient's dentition), among other data. Insome embodiments, the scanner 400 can be configured to scan thepatient's upper and/or lower jaws directly (e.g., intraorally).

The processor 476 in any or all embodiments can be configured to providea visual indication of a virtual dental model on the display 490 (e.g.,on a GUI running on the processor 476 and visible on the display 490).The processor 476 can further be configured (e.g., via computerexecutable instructions stored in a tangible non-transitory computerreadable medium) to perform the various methods, algorithms, and/orfunctionality described herein. The processor 476, in association withthe data storage device 478, can be associated with data and/orapplication modules 494. The processor 476, in association with the datastorage device 478, can store and/or utilize data and/or executeinstructions to provide a number of application modules for confocalimaging using astigmatism.

Such connectivity can allow for the input and/or output of virtualdental model information or instructions (e.g., input via keyboard)among other types of information. Although some embodiments may bedistributed among various computing devices within one or more networks,such systems as illustrated in FIG. 4 can be beneficial in allowing forthe capture, calculation, and/or analysis of information discussedherein.

A system for confocal imaging using astigmatism can include a scanningmodule and a processing module (e.g., processor 476). The scanningmodule can include an intraoral 3D confocal imaging scanner having aparticular astigmatic character.

The processing module (e.g., processor 476) can (e.g., via applicationmodule 494) receive 496 data representing an image pattern associatedwith an image of an object captured by a confocal imaging device (e.g.,confocal imaging device 100) having a particular astigmatic characterand having an image sensor with a plurality of pixels. The processor 476(e.g., via application module 494) can determine 498 a positionalrelationship between the object and a focus plane of the confocalimaging device based on a distribution of the diffraction pattern over aportion of the plurality of pixels, in a manner analogous to thatpreviously discussed in connection with FIGS. 2A and/or 2B, forinstance.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anyarrangement calculated to achieve the same techniques can be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments of thedisclosure.

It is to be understood that the use of the terms “a”, “an”, “one ormore”, “a number of”, or “at least one” are all to be interpreted asmeaning one or more of an item is present. Additionally, it is to beunderstood that the above description has been made in an illustrativefashion, and not a restrictive one. Combination of the aboveembodiments, and other embodiments not specifically described hereinwill be apparent to those of skill in the art upon reviewing the abovedescription.

It will be understood that when an element is referred to as being “on,”“connected to” or “coupled with” another element, it can be directly on,connected, or coupled with the other element or intervening elements maybe present. In contrast, when an element is referred to as being“directly on,” “directly connected to” or “directly coupled with”another element, there are no intervening elements or layers present. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements and that these elementsshould not be limited by these terms. These terms are only used todistinguish one element from another element. Thus, a first elementcould be termed a second element without departing from the teachings ofthe present disclosure.

The scope of the various embodiments of the disclosure includes anyother applications in which the above structures and methods are used.Therefore, the scope of various embodiments of the disclosure should bedetermined with reference to the appended claims, along with the fullrange of equivalents to which such claims are entitled.

In the foregoing Detailed Description, various features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the embodiments of the disclosure requiremore features than are expressly recited in each claim.

Rather, as the following claims reflect, inventive subject matter liesin less than all features of a single disclosed embodiment. Thus, thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separate embodiment.

What is claimed is:
 1. A confocal imaging device, comprising: a sourcelenslet array configured to at least one of focus and collimate lightemitted by a light source array; a beam splitter configured to reflectthe light from the source lenslet array; an object lenslet arrayconfigured to: focus the light from the beam splitter to a point; andre-collimate the light reflected from the focus point; an image lensletarray configured to: receive the re-collimated light from the objectlenslet array; and at least one of focus and collimate the light to animage sensor; wherein the confocal imaging device includes apredetermined astigmatic aberration to asymmetrically focus the lightsuch that the light focused to the image sensor includes a particularasymmetric image pattern to scan a portion of an object.
 2. The confocalimaging device of claim 1, wherein the predetermined astigmaticaberration is located at least one of: adjacent to the light sourcearray; adjacent to the source lenslet array; and adjacent to the imagesensor.
 3. The confocal imaging device of claim 1, wherein the confocalimaging device is configured to convert the particular asymmetric imagepattern to an electronic signal.
 4. The confocal imaging device of claim3, wherein the confocal imaging device is configured to determine adistance between the object and the confocal imaging device based on theelectronic signal.
 5. The confocal imaging device of claim 1, whereinthe image sensor includes a plurality of pixels to produce an electriccharge in response to receiving the light from the image lenslet array.6. The confocal imaging device of claim 1, wherein the confocal imagingdevice is a hand-held intraoral scanner configured to intraorally scan aportion of the object, wherein the object is a tooth.
 7. The confocalimaging device of claim 1, wherein the light source array includes atleast one of: continuous wave lasers; air ion lasers; andsemi-conductive lasers.
 8. A method, comprising: focusing, by a sourcelenslet array of a confocal imaging device, light emitted by a lightsource array on a beam splitter of the confocal imaging device, whereinthe light emitted by the light source follows a light path; reflecting,by the beam splitter, the focused light from the source lenslet array;focusing, by an object lenslet array of the confocal imaging device, thereflected light from the beam splitter to a point to scan a portion of atooth; re-collimating, by the object lenslet array, light reflected fromthe tooth; focusing, by an image lenslet array of the confocal imagingdevice, the re-collimated light from the object lenslet array onto animage sensor of the confocal imaging device, wherein the light focusedon the image sensor includes a particular asymmetric image pattern; anddetermining, by the confocal imaging device based on the particularasymmetric image pattern, a distance between a focus plane of theconfocal imaging device and the portion of the tooth.
 9. The method ofclaim 8, wherein the method includes asymmetrically focusing the lightby a predetermined astigmatic aberration such that the light focused onthe image sensor includes the particular asymmetric image pattern. 10.The method of claim 8, wherein the method includes determining, by theconfocal imaging device, an electric charge produced by the image sensorin response to receiving the particular asymmetric image pattern. 11.The method of claim 10, wherein the method includes determining, by theconfocal imaging device, the distance between the focus plane and theportion of the tooth based on the electric charge of the image sensor.